As a press fit pin (a terminal) having a press fitted region to be press-fitted and connected to a conductive through hole of a printed circuit board, one having the press fitted region, in which substantially parallel beam-like regions are connected by a deformable connection region, is known.
This press fit pin is designed so that, when the press-fitted region is press-fitted to the conductive through hole, outer corner portions of the outer surfaces of the beam-like regions are contacted (pressure-contacted) with the inner wall of the through hole while the connection region is deformed. As a typical example thereof, there is one in which the cross-sectional shape of the press fitted region is formed into an M-shape by the beam-like regions and the connection region (see Japanese Patent Examined Publication No. Sho 60-23471).
The press fit pin of this type is obtained by punching a thin metal plate with die and a punch into a predetermined pin shape, and at the same time molding it into a predetermined cross-sectional shape. In the case of the press fit pin having the press fitted region of M-shape in cross-section, sharpened portions must be provided both in the die and the punch, which correspond to a portion of a downwardly oriented V-shaped valley in the upper central portion thereof, and portions of upwardly oriented V-shaped valleys in the outer lower side thereof, but these shape portions are liable to be damaged during processing of the press fit pin, and thus the punch and die are lowered in durability.
Accordingly, the present inventors and so on of the present application have proposed a technique described in the Japanese Patent No. 2929176 as a press fit pin devised in view of this problem. In this technique, as shown in FIG. 9, a connection region 301 for two beam-like regions 300 and 300 is constructed by a central planar portion 302 extending in a direction substantially perpendicular to the beam-like regions 300 as viewed in a cross-section, and by oblique 303 and 303 extending obliquely outwardly from respective sides of the planar portion 302 and continuous to the respective beam-like regions 300. The press fit pin of the related art as shown in FIG. 9 is not so large in deformable capability of the beam-like regions 300, and an adaptable through hole diameter is limited to a small range.
Additionally, other prior art press fit pins include those disclosed in U.S. Pat. No. 4,762,498 and DE 35 35 074 A1.
However, recently, such a press fit pin has been required that can be adapted to a through-hole of a wide diameter range of, for example, 0.65 mm to 0.8 mm (a range of 0.15 mm) as defined by IEC standards.
Assuming that the conventional press fit pin is applied to the individual conductive through holes having the through hole diameters defined by the IEC standards, a holding force is insufficient with respect to the through hole having the maximum hole diameter of 0.8 mm, and the press-fitted portion may be largely deformed with respect to the through hole of the minimum hole diameter of 0.65 mm to cause a stress concentration and increase in the required insertion force.